1. Field of the Invention
The present invention relates to an ink jet recording apparatus which executes recording by using a recording head which discharges ink. In particular, it relates to an ink jet recording apparatus which includes coloring material-containing ink and reaction liquid that agglutinates when reacted with the coloring material-containing ink.
2. Description of the Related Art
In recent years, along with the spread of information-processing equipment, recording apparatuses have spread rapidly as a peripheral device. Ink jet recording apparatuses use a recording head having a discharge port face on which a plurality of nozzles is arrayed, and recording is executed by causing the recording head to scan a recording medium and discharge ink droplets from discharge ports of the individual nozzles of the recording head during a scanning operation. Such ink jet recording apparatuses have various advantages; for example, they can easily be miniaturized and can execute color recording relatively easily. Thus, these ink jet recording apparatuses have spread rapidly.
Further, there has conventionally been known an ink jet recording apparatus that uses reaction liquid for recording, along with ink containing coloring materials such as cyan, magenta, yellow, and black. Use of such reaction liquid can suppress ink bleed and increase density. However, when a recording head supplied with both of the ink and reaction liquid is used, a mist of reaction liquid and ink attaches to and then firmly adheres to the face of the recording head, easily resulting in a defective discharge. This problematical ink adhesion will be next described with reference to FIGS. 5 and 6.
FIG. 5 is a sectional view of an ink jet recording apparatus, and FIG. 6 illustrates air currents during a preliminary discharge. In FIG. 5, recording is executed by a recording head 3 discharging ink on a recording surface 13 of a recording medium 12, and a preliminary discharge is executed into a preliminary discharge receptacle 8. Moisture of the preliminarily discharged ink is evaporated, and the ink is then thickened and deposited. Since a surface 11 having a discharge port face 3b on the recording head 3 may be smeared by the deposit, the distance between the surface 11 and the preliminary discharge receptacle 8 needs to be greater than the difference between the surface 11 and the recording surface 13 of the recording medium 12.
However, if the distance between the surface 11 and the preliminary discharge receptacle 8 is increased, the ink mist may roll up more easily during a preliminary discharge. As illustrated in FIG. 5, when the distance between the surface 11 and the recording surface 13 is short, the ink mist is relatively small during recording. In contrast, as illustrated in FIG. 6, when the distance between the surface 11 and the preliminary discharge receptacle 8 is large, a greater amount of the ink mist is generated. Further, when both of the ink and the reaction liquid are discharged from adjacent nozzles at the same time, air currents produced due to the discharge are overlapped and increased. Particularly, since all the nozzles discharge ink during a preliminary discharge, large ascending air currents are generated. These ascending air currents roll up and attach the ink mist to the discharge port face 3b. The attached ink and reaction liquid 14 react with each other and adhere to the discharge port face 3b, resulting in a defective discharge.
“Japanese Patent Application Laid-Open No. 2007-253407” proposes a method to solve the above problem. According to the method, by executing preliminary discharges of ink and reaction liquid at different timings, the ink adhesion caused by the reaction between ink and reaction liquid inside a preliminary discharge receptacle is prevented.
However, even when the method discussed in “Japanese Patent Application Laid-Open No. 2007-253407” is used, adhesion of the ink mist, produced by the ink and reaction liquid, to the face of the recording head cannot sufficiently be suppressed, and thus, there is room for improvement. Namely, when bidirectional recording is executed with a recording head on which a reaction liquid discharge port array is arranged on either side of a ink discharge port array, if a preliminary discharge is executed from both of the reaction liquid discharge port arrays, an ink mist of reaction liquid easily attaches to the ink discharge port array. Particularly, when a preliminary discharge is executed while the recording head executes a scanning operation, a mist of the reaction liquid preliminarily discharged from the reaction liquid discharge port array on the front side of the ink discharge port array in a direction in which the recording head travels easily attaches to the ink discharge port array.